A temperature regulation method, system and printing apparatus

Abstract

The application provides a temperature adjusting method, system and printing equipment, and relates to the technical field of temperature control. The method comprises the following steps: obtaining the measurement point temperature of multiple discrete measurement points in a powder region and the environmental temperature of the powder region; constructing a continuous temperature field of the region point temperature of multiple region points according to the measurement point temperature of the multiple discrete measurement points, wherein the number of the region points is greater than the number of the measurement points; dividing the continuous temperature field into multiple sub-regions, and calculating the temperature deviation of each sub-region and the average temperature of the powder region according to the region point temperature of each region point in each sub-region; determining the temperature adjusting instruction of each sub-region according to the temperature deviation of each sub-region, the average temperature of the powder region and the environmental temperature, and sending the temperature adjusting instruction of each sub-region to a temperature adjusting mechanism to control the temperature adjusting mechanism to adjust the temperature of the corresponding sub-region. The application realizes zoned temperature control, thereby guaranteeing the forming stability and the yield.

Description

Technical Field

[0001] This application relates to the field of temperature control technology, and in particular to a temperature regulation method, system and printing equipment. Background Technology

[0002] In Selective Laser Sintering (SLS) 3D printing equipment, excessively high or low powder surface temperatures, or uneven distribution, can severely affect the printing quality. Current solutions primarily rely on the overall average temperature of the powder for uniform temperature control, failing to achieve precise, differentiated temperature adjustment in localized areas. When heat source distribution is uneven or process conditions fluctuate, localized overheating or underheating can easily occur, repeatedly leading to defects such as poor interlayer bonding and warping, making it difficult to guarantee forming stability and yield. Summary of the Invention

[0003] This application provides a temperature regulation method, system, and printing device to at least solve the above-mentioned technical problems existing in the prior art.

[0004] According to a first aspect of this application, a temperature regulation method is provided, the method comprising: The temperature of multiple discrete measurement points within the powder region corresponding to the powder bearing surface of the printing device and the ambient temperature of the powder region are obtained. Based on the temperature of the multiple discrete measurement points, a continuous temperature field is constructed for the powder region. The continuous temperature field includes the temperature of multiple regional points, and the number of regional points is greater than the number of measurement points. The continuous temperature field is divided into multiple sub-regions, and the temperature deviation of each sub-region and the average temperature of the powder region are calculated based on the temperature of each region point within each sub-region. Based on the temperature deviation of each sub-region, the average temperature of the powder region, and the ambient temperature, a temperature adjustment command for each sub-region is determined, and the temperature adjustment command for each sub-region is sent to the temperature adjustment mechanism. The temperature adjustment command is used to control the temperature adjustment mechanism to adjust the temperature of the corresponding sub-region.

[0005] In one possible implementation, obtaining the temperature of multiple discrete measurement points within the powder region corresponding to the powder bearing surface of the printing device includes: Acquire the voltage data measured by each thermocouple located at each discrete measurement point; Based on the voltage data measured by each thermocouple and the preset voltage-temperature mapping relationship, the measurement point temperature of each discrete measurement point is determined.

[0006] In one possible implementation, acquiring the voltage data measured by each thermocouple arranged at each discrete measurement point includes: Obtain the original voltage signals output by each thermocouple at each discrete measurement point; The original voltage signals output by each thermocouple are amplified, cold junction compensated, and second-order low-pass filtered to obtain the voltage data measured by each thermocouple.

[0007] In one embodiment, constructing a continuous temperature field for the powder region based on the measurement point temperatures of the plurality of discrete measurement points includes: Obtain the weight matrix of the powder region, the weight matrix including the weight coefficient of each region point in the powder region relative to each discrete measurement point; The measurement point temperature of each discrete measurement point is calculated by matrix operation based on the weight matrix to obtain the regional point temperature of each region, forming a continuous temperature field covering the powder region.

[0008] In one possible implementation, the weight matrix is ​​obtained through the following operation: The powder region is discretized into multiple region points; Based on the location data of each regional point and each discrete measurement point, calculate the relative position of each regional point with respect to each discrete measurement point, as well as the relative position between each discrete measurement point; Construct a coefficient matrix based on the radial basis functions and the relative positions of each discrete measurement point; Based on the radial basis function and the relative positions of each region point with respect to each discrete measurement point, determine the position influence vector of each region point; Based on the position influence vector of each region point and the coefficient matrix, the weight coefficient of each region point relative to each discrete measurement point is determined, and the weight coefficients of each discrete measurement point are concatenated to form the weight matrix.

[0009] In one possible implementation, dividing the continuous temperature field into multiple sub-regions and calculating the temperature deviation of each sub-region and the average temperature of the powder region based on the temperature of each region point within each sub-region includes: The continuous temperature field is divided into multiple non-overlapping sub-regions according to a preset division rule; Calculate the overall average temperature of all regional points to obtain the average temperature of the powder region; Calculate the average temperature of all points within each sub-region to obtain the average temperature of each sub-region; The temperature deviation of each sub-region is determined based on the average temperature of each sub-region and the average temperature of the powder region.

[0010] In one possible implementation, determining the temperature adjustment command for each sub-region based on the temperature deviation of each sub-region, the average temperature of the powder region, and the ambient temperature includes: Based on the temperature deviation of each sub-region and the preset deviation threshold, multiple sub-regions are divided into types to be adjusted and normal types. For the sub-region of the type to be adjusted, the additional control quantity of each sub-region is determined according to the temperature deviation and partition gain coefficient of each sub-region, and the additional control quantity of the partition of the normal type sub-region is set to zero. Calculate the global temperature deviation based on the average temperature of the powder region and the target temperature; Based on the global temperature deviation and global gain parameters, determine the global feedback control quantity; The environmental feedforward compensation amount is determined based on the ambient temperature, the reference ambient temperature, and the feedforward coefficient. The total global control quantity is determined based on the global feedback control quantity and the environmental feedforward compensation quantity. Based on the global total control quantity and the zone additional control quantity, a temperature adjustment command for each sub-region is constructed, and the temperature adjustment command carries the global total control quantity and the zone additional control quantity.

[0011] In one possible implementation, the temperature regulating mechanism regulates the temperature of the corresponding sub-region through the following operations: In response to the global total control quantity being greater than or equal to zero in the temperature adjustment command, the heating mode is entered. The global total control quantity is used as the global heating power reference, and the additional control quantity of each sub-region is superimposed to obtain the final heating power of each sub-region. Heating is performed on the corresponding sub-region according to the final heating power. In response to the global total control quantity in the temperature adjustment command being less than zero, the system enters cooling mode and uses the absolute value of the global total control quantity as the cooling intensity to perform uniform cooling on all sub-regions.

[0012] According to a second aspect of this application, a temperature regulation system is provided, the system comprising: A flexible, high-temperature resistant insulating support layer is attached to the powder-bearing surface of the printing equipment; An ambient temperature sensor is arranged on the side of the powder bearing surface without contacting the powder, and is connected to the main control unit to collect the ambient temperature of the powder area corresponding to the powder bearing surface. An irregularly distributed thermocouple array, mounted on the flexible high-temperature resistant insulating support layer and connected to the main control unit, includes multiple thermocouples. Each thermocouple's measuring end is fitted with a metal protective cover, which is in direct contact with the powder, so that the thermocouples indirectly measure the voltage signal of discrete measuring points at corresponding locations through the metal protective cover, allowing the main control unit to obtain the temperature of each discrete measuring point based on the voltage signal. A signal conditioning unit is connected between the irregular distributed thermocouple array and the main control unit. It is used to amplify the voltage signal, compensate for the cold junction, and perform second-order low-pass filtering to obtain the voltage data at the discrete measurement points corresponding to each thermocouple. The main control unit is connected to the irregular distributed thermocouple array, the ambient temperature sensor and the temperature regulation mechanism respectively, and is used to execute the temperature regulation method described in this application. A temperature regulation mechanism, connected to the main control unit, is used to regulate the temperature of each sub-region according to temperature regulation commands.

[0013] According to a third aspect of this application, a printing apparatus is provided, including the temperature control system described above.

[0014] This application's temperature control method, system, and printing equipment acquire discrete measurement point temperatures and ambient temperatures, construct a continuous temperature field, divide it into sub-regions, calculate the temperature deviation of each sub-region and the average temperature of the powder region, and then combine the sub-region temperature deviations, average temperatures, and ambient temperatures to generate temperature control commands for each sub-region. This achieves differentiated and precise temperature control at different locations within the powder region. It solves the problem of localized overheating or underheating caused by relying solely on single-point or global average temperatures for unified control in existing technologies, significantly improving the spatial consistency and control accuracy of the powder surface temperature, and effectively ensuring molding stability and yield.

[0015] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0016] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which: In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0017] Figure 1 A schematic diagram of the composition structure of the temperature regulation system provided in an embodiment of this application is shown; Figure 2 This illustration shows a planar arrangement diagram of an irregular distributed thermocouple array provided in an embodiment of this application; Figure 3 A cross-sectional view of the assembly of a single-channel thermocouple and a protective cover in an embodiment of this application is shown; Figure 4 A schematic diagram of the composition structure of the printing device provided in an embodiment of this application is shown; Figure 5 A schematic diagram illustrating the implementation flow of the temperature regulation method provided in an embodiment of this application is shown; Figure 6 This paper illustrates a schematic diagram of the implementation process of the temperature field construction operation of the temperature regulation method provided in the embodiments of this application; Figure 7 A schematic diagram illustrating the implementation flow of the instruction generation operation of the temperature regulation method provided in this application embodiment is shown; Figure 8 An example diagram of a 4×4 partition labeling of a top view of the powder region in an embodiment of this application is shown. Detailed Implementation

[0018] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] First, the application scenarios of this application will be explained. In selective laser sintering (SLS) 3D printing equipment, if the powder surface temperature is too low, the laser energy cannot effectively melt the powder particles, easily resulting in weak interlayer bonding, increased porosity, and insufficient mechanical strength of the parts. If the powder surface temperature is too high, it will cause premature sintering, agglomeration, or even thermal degradation of the powder, leading to warping and deformation of the parts, and in severe cases, directly causing printing failure. If the powder surface temperature distribution is uneven, with differences in the degree of melting in local areas, it will cause internal stress accumulation, deviation of the finished product dimensions from design requirements, and a significant reduction in the forming accuracy and reliability of the parts. Therefore, precise control of the powder surface temperature is a core prerequisite for ensuring the forming quality of SLS 3D printing.

[0020] Currently, powder surface temperature control largely relies on closed-loop feedback control using single-point temperature or overall average temperature. This fails to consider spatial non-uniform disturbances such as changes in powder flow velocity, cumulative thermal inertia from multiple powder layers, and uneven heat source distribution. This can easily lead to localized overheating or underheating in the powder area, resulting in frequent molding defects such as poor interlayer bonding and warping. During prolonged equipment operation, the power attenuation of heating devices further exacerbates temperature field drift. Furthermore, existing technologies lack the ability to reconstruct the spatial distribution of the temperature field and a multi-source disturbance feedforward compensation mechanism, ultimately resulting in low printing yield, long process debugging cycles, and high equipment maintenance costs.

[0021] To address the aforementioned technical issues, a reusable surface temperature measuring grid device for powder bed additive manufacturing has been proposed. The device primarily employs a double-layer composite substrate combined with a thermocouple grid structure. The upper layer of the composite substrate is a modified polytetrafluoroethylene (PTFE) sheet with a thickness of 0.5–1.0 mm, possessing non-stick, high-temperature resistant, and insulating properties. The surface of the sheet has a micro-recessed grid structure for fixing the thermocouples without interfering with normal powder spreading operations. The lower layer is an alumina ceramic substrate with high rigidity, low thermal expansion coefficient, high temperature resistance, insulation, and uniform thermal conductivity, primarily serving as structural support, thermal insulation, and inhibiting high-temperature creep of the PTFE. The upper and lower substrates are bonded together with a high-temperature inorganic adhesive. The built-in thermocouple grid uses armored K-type thermocouple wires, distributed in a matrix pattern, embedded within the PTFE micro-recesses and flush with the powder bed surface. The thermocouple leads are routed along the edge of the ceramic substrate and sealed out to avoid interference with the powder spreading process.

[0022] However, the aforementioned technologies still have drawbacks: First, the rigid substrate structures made of polytetrafluoroethylene, ceramics, or metals are inflexible, have poor surface adhesion, and are prone to gaps between the substrate and the piston plate of the molding cylinder, failing to accurately reflect the actual temperature field of the powder surface under the coupled heating of the molding cylinder and the surface. Second, the rigid substrate requires precise calibration of its height and installation position during installation; misalignment can easily lead to collisions with the powder spreading mechanism, resulting in device damage. Therefore, this application provides a temperature regulation method, system, and printing equipment to address the pain points of existing technologies. This method can accurately collect and characterize the true temperature of the powder surface, achieve simple installation and disassembly, and is reusable.

[0023] Figure 1 A schematic diagram of the composition structure of the temperature regulation system provided in an embodiment of this application is shown.

[0024] refer to Figure 1This application first proposes a temperature control system, also known as a powder surface temperature distributed flexible temperature measurement and intelligent closed-loop control system. The system includes a flexible high-temperature resistant insulating support layer (not shown in the figure), an ambient temperature sensor, an irregular distributed thermocouple array, a main control unit, and a temperature adjustment mechanism.

[0025] The flexible, high-temperature resistant insulating support layer is attached to the powder-bearing surface of the printing equipment. It is made of mica composite flexible insulating material, contains no PTFE or rigid ceramic substrate, can be bent to fit the powder-bearing surface, has a temperature resistance of ≥500℃, and produces no volatile pollution. The powder-bearing surface refers to the surface of the printing equipment that directly supports and bears the powder layer. The space covered by the powder layer above the powder-bearing surface is the powder area requiring temperature detection and control in this embodiment.

[0026] The ambient temperature sensor is positioned to the side of the powder-supporting surface without contacting the powder, specifically at a distance of 50mm from the powder bed. It connects to the main control unit to collect the ambient temperature of the powder area corresponding to the powder-supporting surface, which is then used by the main control unit.

[0027] An irregularly distributed thermocouple array is mounted on a flexible, high-temperature resistant insulating support layer and connected to the main control unit. The array comprises multiple thermocouples, each corresponding to a discrete measurement point. The measurement point locations follow a Poisson disk sampling or low-difference sequence (such as a Halton sequence) distribution, with no three points collinear and adjacent spacing of 10–80 mm, effectively avoiding the spectral aliasing problem of regular grids. The temperature-sensing end of each thermocouple is placed inside a metal protective cover, with the top of the cover tightly bonded to the thermocouple end face using thermally conductive silicone. The metal protective cover is in direct contact with the powder. The cover can be made of stainless steel or nickel-based alloy with a thickness of 0.1–0.3 mm, providing good thermal conductivity and wear resistance, completely preventing direct contact between the powder and the thermocouple, thus effectively avoiding wear, jamming, and electrostatic interference. The thermocouples indirectly measure the voltage signal at the corresponding discrete measurement point through the metal protective cover, allowing the main control unit to obtain the temperature at each discrete measurement point based on the voltage signal.

[0028] To further understand the arrangement of the irregular distributed thermocouple array and the assembly structure of the single thermocouple and protective cover in the embodiments of this application, the following is combined with Figure 2 and Figure 3 An example is provided.

[0029] refer to Figure 2 , Figure 2 This illustration shows a planar arrangement of an irregularly distributed thermocouple array according to an embodiment of this application. Taking 16 thermocouples as an example, the discrete measurement points corresponding to each thermocouple are irregularly distributed on the powder support surface. The measurement point locations can be obtained using Poisson disk sampling or low-difference sequences (such as...). Figure 2The sample points are arranged in a Halton sequence as shown, with no three points collinear and the distance between adjacent points ranging from 10 mm to 80 mm. This irregular, non-matrix layout, compared to the traditional regular grid, can effectively avoid the spectral aliasing problem caused by improper matching between the sampling frequency and the thermal field spatial frequency, thus more realistically restoring the actual temperature distribution on the powder surface. Figure 2 The center coordinates (unit: mm) of some measuring points are marked for example, such as (50, 50), (110, 180), (128, 92), etc., and the boundary of the temperature measuring area on the powder surface and the edge blank area (e.g. ≥8mm) are clearly defined to ensure that the temperature measuring area covers the effective powder range (e.g. 280×280) and does not affect the edge powder spreading action.

[0030] refer to Figure 3 , Figure 3 This diagram shows a cross-sectional view of the assembly of a single-channel thermocouple and its protective cover in an embodiment of this application. The thermocouple, also known as a K-type thermocouple, has its upper surface of the printing piston heating plate ⑤ forming a powder support surface, on which the powder layer ① is directly laid. A flexible, high-temperature resistant insulating support layer ④ is tightly fitted between the powder support surface and the powder layer ①. The temperature-sensing end of the K-type thermocouple ③ is fitted inside the metal protective cover ②, with the top of the metal protective cover ② tightly fitted to the thermocouple's temperature-sensing end, while the cover itself is in direct contact with the powder layer ①. When the powder temperature changes, heat is first conducted through the metal protective cover ② to the K-type thermocouple ③, achieving indirect, non-contact temperature measurement. This arrangement effectively blocks direct friction, impact, and electrostatic interference between the powder particles and the thermocouple body, significantly extending the thermocouple's service life while avoiding mechanical interference from the thermocouple during the powder laying process.

[0031] The signal conditioning unit is connected between the irregularly distributed thermocouple array and the FPGA of the main control unit, and is a unit within the main control unit. It is used to amplify the voltage signals acquired by the thermocouples, perform cold junction compensation, and perform second-order low-pass filtering to obtain the voltage data at the discrete measurement points corresponding to each thermocouple.

[0032] The main control unit is connected to the irregular distributed thermocouple array, the ambient temperature sensor, and the temperature regulation mechanism, respectively, and is used to execute the temperature regulation method of this application. The main control unit includes an MCU (Microcontroller Unit) and an FPGA (Field-Programmable Gate Array). Among them, the FPGA is responsible for multi-channel synchronous sampling and filtering, while the MCU is responsible for temperature field reconstruction, zone control, PID control, and feedforward.

[0033] The temperature regulation mechanism is connected to the MCU of the main control unit and is used to regulate the temperature of each sub-region according to temperature regulation commands. The temperature regulation mechanism includes: a zone-independent control heater (such as a 4×4 zone infrared lamp), a cooling module (air-cooled / water-cooled), and a conveying speed regulation module (such as a powder spreading roller motor). Among them, the zone-independent control heater is used to heat the corresponding local area within the powder area, the cooling module is used to cool the powder area, and the conveying speed regulation module is used to adjust the powder conveying speed.

[0034] Thus, the embodiments of this application, through the innovative design of a flexible high-temperature resistant insulating support layer and the irregular distributed thermocouple array arrangement, avoid reliance on a rigid substrate, enabling seamless bonding between the temperature measuring structure and the powder bearing surface, and accurately capturing the true temperature distribution on the powder surface.

[0035] Figure 4 A schematic diagram of the composition structure of the printing device provided in the embodiments of this application is shown.

[0036] Based on the aforementioned temperature control system, this application also provides a printing device, including the aforementioned temperature control system. The printing device includes a powder layer ①, a metal protective cover ②, a K-type thermocouple ③, a flexible high-temperature resistant insulating support layer ④, a printing piston heating plate ⑤, a surface heating device ⑥, an inlet fan ⑦, an outlet fan ⑧, a powder spreading device ⑨, and an ambient temperature sensor ⑩. The flexible high-temperature resistant insulating support layer is a flexible mica support layer; the surface heating device ⑥ is the zoned independently controlled heater of the aforementioned temperature control mechanism; the inlet fan ⑦ and the outlet fan ⑧ constitute a cooling module; and the powder spreading device ⑨ is the conveying speed control module of the aforementioned temperature control mechanism. The printing device in this application may include, but is not limited to, SLS equipment, Selective Laser Melting (SLM) equipment, Electron Beam Melting (EBM) equipment, and other powder bed-based additive manufacturing equipment.

[0037] The upper surface of the printing piston heating plate ⑤ forms the powder bearing surface; the flexible high-temperature resistant insulating support layer ④ is tightly attached to the powder bearing surface; the K-type thermocouple ③ is embedded in the flexible high-temperature resistant insulating support layer ④, and its temperature measuring end is fitted inside the metal protective cover ②. The top of the metal protective cover ② is in direct contact with the powder layer ①, so that the K-type thermocouple ③ can indirectly measure the temperature of the surface of the powder layer ① through the metal protective cover ②; the powder layer ① is laid on top of the flexible high-temperature resistant insulating support layer ④; the surface heating device ⑥ is set on top of the powder layer ① for zoned heating of the powder surface; the inlet fan ⑦ and the outlet fan ⑧ constitute a cooling module, which can perform air cooling for the inside of the equipment; the powder spreading device ⑨ is used to complete the powder spreading operation; the ambient temperature sensor ⑩ is arranged on the side of the powder bearing surface and does not contact the powder, and is used to collect the ambient temperature.

[0038] During the printing process, a K-type thermocouple ③ collects the voltage signal from the surface of the powder layer ① through a metal protective cover ②, and an ambient temperature sensor ⑩ collects the ambient temperature. After the two signals are sent to the main control unit, they undergo signal conditioning, multi-channel sampling, and temperature field reconstruction to generate temperature adjustment commands for each sub-region. The sub-regions are obtained by dividing the powder area into zones. Based on these commands, the main control unit controls the surface heating device ⑥ to perform zoned heating, or controls the inlet fan ⑦ and outlet fan ⑧ to perform cooling actions. Simultaneously, the powder spreading device ⑨ can adjust the powder spreading speed, achieving closed-loop precise control of the powder surface temperature and ensuring the forming quality and yield of SLS printing.

[0039] It should be noted that the description of the system and printing equipment in the embodiments of this application is similar to the description of the method embodiments below, and has similar beneficial effects as the method embodiments, therefore, it will not be repeated. For any technical details not covered in the temperature control system and printing equipment provided in the embodiments of this application, please refer to... Figures 5 to 8 The meaning is understood in accordance with the description of any of the accompanying drawings.

[0040] Figure 5 A schematic diagram illustrating the implementation flow of the temperature regulation method provided in this application embodiment is shown.

[0041] refer to Figure 5 This application provides a temperature regulation method, executed by the main control unit of the aforementioned temperature regulation system or printing device, the method comprising: Operation 101: Obtain the temperature of multiple discrete measurement points within the powder area corresponding to the powder bearing surface of the printing device, as well as the ambient temperature of the powder area.

[0042] In one embodiment of this application, obtaining the measurement point temperature of multiple discrete measurement points within the powder area of ​​the printing device includes: obtaining voltage data measured by each thermocouple arranged at each discrete measurement point; and determining the measurement point temperature of each discrete measurement point based on the voltage data output by each thermocouple and a preset voltage-temperature mapping relationship.

[0043] In one embodiment of this application, acquiring voltage data measured by each thermocouple arranged at each discrete measurement point includes: acquiring the original voltage signal output by each thermocouple at each discrete measurement point; and performing signal amplification, cold junction compensation, and second-order low-pass filtering on the voltage signal output by each thermocouple to obtain the voltage data measured by each thermocouple.

[0044] The powder bearing surface of the printing equipment is the supporting surface that directly supports the powder layer, and the powder area is the effective working area on the powder bearing surface used for SLS laser sintering. Within the powder area, based on the powder temperature field distribution characteristics and powder spreading process requirements, multiple discrete measurement points are empirically selected near the inner part of the effective forming area. Thermocouples are placed at each discrete measurement point, forming an irregular distributed thermocouple array. During normal operation of the printing equipment, each thermocouple senses the temperature change at its corresponding discrete measurement point in real time and outputs a raw voltage signal.

[0045] Because the original voltage signal output by thermocouples has a weak amplitude, is susceptible to electromagnetic interference and significant temperature drift, it is difficult for the main control unit to directly identify and process it. Therefore, in this embodiment, after acquiring the original voltage signal of the thermocouple, the original voltage signal is first subjected to signal amplification, cold junction compensation, and second-order low-pass filtering in sequence. This filters out high-frequency interference, compensates for cold junction temperature drift, and amplifies the effective signal amplitude, resulting in voltage data for each thermocouple's corresponding discrete measurement points with a high signal-to-noise ratio that can be directly used in calculations. Signal amplification and cold junction compensation can be implemented using a dedicated cold junction compensation amplifier, with the signal amplification factor exemplarily set to 100 times. The second-order low-pass filtering is implemented using a moving average filtering method, performing mean filtering according to a preset sliding sampling window. The sliding window length can be exemplarily set to 5 times, and this application does not specifically limit this.

[0046] While the thermocouple acquires the original voltage signal, an ambient temperature sensor positioned on the side of the powder bearing surface simultaneously acquires the ambient temperature around the powder area for subsequent feedforward compensation control. In this embodiment, the FPGA inside the main control unit is responsible for synchronously acquiring the conditioned voltage data and ambient temperature. The sampling frequency can be configured to 20Hz, but in actual applications, it can be flexibly configured according to process requirements, and this application does not limit it. The MCU of the main control unit reads the voltage data and ambient temperature of each discrete measurement point from the FPGA according to a preset cycle, and calculates the measurement point temperature of each discrete measurement point based on the preset voltage-temperature mapping relationship, and then executes subsequent calculations and control logic. The MCU can be configured to read data from the FPGA once every 50ms. The measurement point temperature is the actual temperature value of the discrete measurement point, and the voltage data is the voltage value.

[0047] The preset voltage-temperature mapping relationship refers to the conversion rule between voltage signals and corresponding temperature values, which can be configured empirically. For example, the mapping relationship could be: output voltage 0~5V corresponds to temperature 0~500℃. After reading the voltage data from each channel, the MCU calculates the corresponding actual temperature value through linear interpolation (or table lookup). For voltage values ​​outside the calibrated range, endpoint extrapolation or amplitude limiting is used to ensure the integrity of the mapping.

[0048] Operation 102: Based on the measurement point temperatures of multiple discrete measurement points, construct a continuous temperature field for the powder region. The continuous temperature field includes the region point temperatures of multiple region points, and the number of region points is greater than the number of measurement points.

[0049] The aforementioned steps can only obtain the temperature values ​​of a limited number of discrete measurement points within the powder area. The number of discrete measurement points is sparse and their spatial distribution is limited, which can only characterize the temperature state at individual locations and cannot fully and accurately depict the continuous temperature distribution and changes of the entire powder surface.

[0050] To achieve a refined characterization of the global temperature field, this embodiment, based on the temperature of a finite number of discrete measurement points, uses spatial interpolation fitting to generate a much larger number of regional points (e.g., 16 discrete measurement points and 2500 regional points in a 50×50 grid) across the entire powder region. By spatial location correlation and temperature interpolation calculation, the temperature of each regional point is obtained, thereby forming a global temperature field that covers the entire powder region and has a continuous temperature transition.

[0051] This continuous temperature field can reproduce the true temperature gradient, local high-temperature zone and low-temperature zone distribution on the powder surface, making up for the shortcoming that sparse measurement points cannot cover the entire area, and providing complete and detailed temperature base data for subsequent sub-region division and zone temperature calculation.

[0052] Operation 103 divides the continuous temperature field into multiple sub-regions, and calculates the temperature deviation of each sub-region and the average temperature of the powder region based on the regional point temperature of each region within each sub-region.

[0053] The reconstructed continuous temperature field covers the entire effective forming area of ​​the powder. In order to achieve precise temperature control with local differences, this embodiment divides the entire continuous temperature field into several sub-regions of moderate size, independent of each other and non-overlapping, according to the forming process and heating zone layout rules.

[0054] The average temperature of all points in the continuous temperature field is calculated separately and used as the overall average temperature of the entire powder region, representing the overall temperature benchmark level of the powder. At the same time, the average temperature of all points in each sub-region is calculated separately and used as the representative temperature of each sub-region.

[0055] Using the overall average temperature of the powder region as a reference, the deviation of the actual average temperature of each sub-region is compared to quantify the temperature deviation of each sub-region. This is used to characterize the degree of local relative heat or cold, providing a quantitative basis for the generation of subsequent zone control commands.

[0056] Operation 104: Based on the temperature deviation of each sub-region, the average temperature of the powder region, and the ambient temperature, determine the temperature adjustment command for each sub-region, and send the temperature adjustment command for each sub-region to the temperature adjustment mechanism. The temperature adjustment command is used to control the temperature adjustment mechanism to adjust the temperature of the corresponding sub-region.

[0057] The quality of powder forming is simultaneously affected by the overall temperature level of the powder bed, the temperature differences in local sub-regions, and the fluctuations in the ambient temperature. This application's embodiments comprehensively incorporate the local temperature deviations of each sub-region, the overall average temperature of the powder region, and the real-time ambient temperature, performing multi-dimensional coupled calculations.

[0058] Taking into account the overall temperature steady-state control requirements, the local temperature difference abnormality correction requirements, and the environmental temperature disturbance compensation requirements, the temperature adjustment instructions for each sub-region are calculated and generated in a coordinated manner, and the generated temperature adjustment instructions are sent to the temperature adjustment mechanism.

[0059] After receiving the adjustment command, the temperature control mechanism performs matching heating, heat preservation, or moderate cooling control actions on the corresponding sub-region that needs to be adjusted, thereby achieving a coordinated control effect of overall temperature stability and local temperature uniform correction of the powder region, effectively suppressing forming defects such as warping, deformation, and poor interlayer bonding caused by uneven temperature.

[0060] The temperature regulation command can carry the following information: the target heating power for each sub-region (used to control the independent heating output of the heater in each zone), the cooling intensity (used to control the airflow or water valve opening of the cooling module), and the conveying speed regulation (used to control the speed of the powder spreading roller motor and adjust the powder conveying speed). Using these parameters, the temperature regulation mechanism can perform differentiated actions such as heating, heat preservation, cooling, or speed regulation for different sub-regions. These parameters can be obtained using PID (Proportional-Integral-Derivative) control to achieve closed-loop regulation of the powder zone temperature and conveying speed.

[0061] Thus, this embodiment first synchronously collects the temperature of discrete measurement points in the powder region and the ambient temperature, and then reconstructs a continuous and detailed global temperature field by interpolation of sparse measurement point data; then, the temperature field is divided into sub-regions, and the temperature deviation of each sub-region and the overall average temperature of the powder are quantified respectively; finally, by comprehensively considering local temperature deviations, overall temperature levels, and environmental disturbances, a dedicated temperature adjustment command for each sub-region is generated and issued for execution. This approach abandons the traditional extensive mode of relying solely on unified control of single-point or average temperatures, and can take into account both the overall steady-state temperature of the powder and the differential correction of local regions. It can suppress temperature field shifts caused by environmental fluctuations and process disturbances in real time, effectively improve local overheating and underheating problems, thereby ensuring uniform and stable surface temperature of SLS-printed powder, reducing forming defects such as poor interlayer bonding and warping deformation, and improving forming stability and printing yield.

[0062] Figure 6 This paper illustrates a schematic diagram of the implementation process of the temperature field construction operation of the temperature regulation method provided in the embodiments of this application.

[0063] refer to Figure 6 In one embodiment of this application, a continuous temperature field of the powder region is constructed based on the measurement point temperatures of multiple discrete measurement points, including: Operation 201: Obtain the weight matrix of the powder region. The weight matrix includes the weight coefficients of each region point within the powder region relative to each discrete measurement point.

[0064] In one embodiment of this application, the weight matrix is ​​obtained through the following operations: discretizing the powder region into multiple region points; calculating the relative position of each region point relative to each discrete measurement point and the relative position between each discrete measurement point based on the position data of each region point and each discrete measurement point; constructing a coefficient matrix based on the radial basis function and the relative position between each discrete measurement point; determining the position influence vector of each region point based on the radial basis function and the relative position of each region point relative to each discrete measurement point; determining the weight coefficient of each region point relative to each discrete measurement point based on the position influence vector of each region point and the coefficient matrix, and concatenating the weight coefficients of each discrete measurement point into a weight matrix.

[0065] To achieve rapid reconstruction of the continuous temperature field from sparse discrete measurement points, this application pre-constructs a weight matrix and stores it in the MCU. Each element in the weight matrix represents the weight coefficient of a certain region point in the powder area relative to a certain discrete measurement point. During online operation, the temperature values ​​of all region points can be obtained simply by multiplying the measured temperatures of each discrete measurement point with the weight matrix.

[0066] The weight matrix was obtained through the following offline pre-computation method: First, the powder region is discretized into multiple region points. For example, the surface corresponding to the powder bearing surface can be discretized into a 50×50 grid, with a total of 2500 region points.

[0067] Then, based on the location data of each regional point and each discrete measurement point, the relative position (i.e., Euclidean distance) of each regional point with respect to each discrete measurement point, as well as the relative position between each discrete measurement point, are calculated.

[0068] Next, a coefficient matrix is ​​constructed based on the radial basis functions and the relative positions of the discrete measurement points. This application uses a multiquadric function as the radial basis function, and its expression is: ,in Distance (unit: mm) Here is the kernel width parameter (unit: mm). To obtain the optimal kernel width parameter, leave-one-out cross-validation (LOOCV) is used to search within the range of 5 mm to 50 mm. For example, using 16 thermocouples (i.e., 16 discrete measurement points) as a sample, optimization is achieved... Coefficient matrix Each element is ,in , These are the coordinates of the discrete measurement points.

[0069] Simultaneously, based on the radial basis functions and the relative positions of each region point with respect to each discrete measurement point, the positional influence vector of each region point is determined. For a given region point (the point to be interpolated)... Its position influence vector The component is That is, the radial basis function value between the point in the region and each discrete measurement point.

[0070] Then, based on the positional influence vectors and coefficient matrices of each region point, the system of linear equations is solved. The weighting coefficients of the points in this region relative to each discrete measurement point are obtained. ,in Let be the number of discrete measurement points. These weighting coefficients satisfy the following: for any point in the region, its reconstructed temperature... , These are the measured temperature values ​​at discrete measurement points.

[0071] Finally, the weight coefficients of all regional points (e.g., 2500 grid points) within the powder area are concatenated row by row to form a complete weight matrix. (Dimensions are 2500×16). This weight matrix is ​​pre-calculated and stored in the MCU's Flash memory.

[0072] Operation 202 involves performing matrix operations on the temperature of each discrete measurement point based on the weight matrix to obtain the regional temperature of each area, thus forming a continuous temperature field covering the powder area.

[0073] After obtaining the pre-computed weight matrix, during the online run phase, the temperature field reconstruction degenerates into simple matrix multiplication. The MCU collects the temperature at each discrete measurement point at the current moment and constructs a measured temperature vector. This vector is compared with a pre-stored weight matrix. By multiplying, the temperature of all points within the powder region can be calculated at once, thus quickly reconstructing a continuous temperature field covering the entire powder region. .

[0074] For example, the powder region is discretized into 2500 points (50×50), using 16 discrete measurement points (thermocouples), with a weight matrix dimension of 2500×16. Online matrix multiplication requires 40,000 multiply-accumulate operations. In actual MCU testing, this calculation takes only about 2.3ms, far exceeding the upper limit required for real-time control, such as 5ms. Therefore, this operation can reconstruct a high-resolution temperature field in a very short time, providing timely and accurate temperature distribution information for subsequent real-time zoned temperature adjustment.

[0075] Thus, by pre-calculating and storing the weight matrix, the embodiments of this application transform complex spatial interpolation calculations into simple matrix multiplications in the online stage, significantly reducing the online computational burden while ensuring reconstruction accuracy, and meeting the real-time requirements for temperature feedback control in the additive manufacturing process.

[0076] In one embodiment of this application, the above-mentioned operation 103 divides the continuous temperature field into multiple sub-regions, and calculates the temperature deviation of each sub-region and the average temperature of the powder region based on the temperature of each region point within each sub-region. This includes: dividing the continuous temperature field into multiple non-overlapping sub-regions according to a preset division rule; calculating the overall average value of the temperature of all region points to obtain the average temperature of the powder region; calculating the average value of the temperature of all region points within each sub-region to obtain the average temperature of each sub-region; and determining the temperature deviation of each sub-region based on the average temperature of each sub-region and the average temperature of the powder region.

[0077] First, the continuous temperature field is divided into multiple non-overlapping sub-regions according to a preset division rule, with each sub-region corresponding to an independent and controllable heating zone. Then, the average temperature of all points within each sub-region is calculated to obtain the average temperature of each sub-region; simultaneously, the overall average temperature of all points is calculated to obtain the average temperature of the powder region (i.e., the overall average temperature). Next, the average temperature of each sub-region is subtracted from the average temperature of the powder region to obtain the temperature deviation of each sub-region. A positive deviation indicates that the sub-region is relatively hot, and a negative deviation indicates that it is relatively cold. The preset division rule refers to the spatial division method of the continuous temperature field into multiple sub-regions. For example, the powder region can be divided into 16 rectangular sub-regions (4 rows × 4 columns) with equal spacing, each corresponding to an independent and controllable heating zone; alternatively, a non-uniform division (e.g., a denser division in the central region and a sparser division at the edges) can be used based on the heat source distribution or process requirements. This application does not specifically limit this approach.

[0078] For example, a 4×4 partitioning scheme can be used as the preset partitioning rule to divide the reconstructed continuous temperature field, such as 2500 regional points, into 16 sub-regions according to spatial affiliation, and the average temperature Ti of each sub-region can be calculated. Then, the average temperature of the powder region and the temperature deviation of the sub-regions can be calculated based on the following formula: Average temperature across the venue: Tavg= ; Sub-region temperature deviation: ΔTi = Ti - Tavg.

[0079] Figure 7 The diagram illustrates the implementation flow of the instruction generation operation of the temperature regulation method provided in this application embodiment.

[0080] In one embodiment of this application, the above-described operation 104, based on the temperature deviation of each sub-region, the average temperature of the powder region, and the ambient temperature, determines the temperature adjustment command for each sub-region, including: Operation 301: Based on the temperature deviation of each sub-region and the preset deviation threshold, divide multiple sub-regions into adjustment type and normal type.

[0081] This application embodiment pre-configures a preset deviation threshold, which can be configured to include a positive threshold and a negative threshold. For example, the positive threshold is set to... The negative threshold is set to Based on the temperature deviation of each sub-region The comparison results with these two thresholds can divide multiple sub-regions into two types: those to be adjusted and those that are normal. The types to be adjusted further include hot spot types and cold spot types. when When the threshold is positive, it indicates that the temperature of the sub-region is significantly higher than the average temperature of the entire field, and it is identified as a hot spot type. The corresponding sub-region can be called a hot spot region.

[0082] when When the threshold is negative, it indicates that the temperature of the sub-region is significantly lower than the average temperature of the entire field, and it is identified as a cold zone type. The corresponding sub-region can be called a cold zone region.

[0083] when When the threshold (i.e., between the negative and positive thresholds) is reached, it indicates that the temperature deviation is within an acceptable range and is determined to be of the normal type. The corresponding sub-region can be called the normal region.

[0084] For example, if the positive threshold is configured as Negative threshold is ,but: like This area was identified as a hotspot (type to be adjusted). like This area is identified as a cold zone (type to be adjusted). otherwise( This area was determined to be within the normal range.

[0085] After the type classification is completed, the type distribution pattern of each sub-region of the powder region can be referenced. Figure 8 . Figure 8 This paper shows a 4×4 partitioned diagram of a top view of the powder region in an embodiment of this application, with each grid cell labeled with the actual temperature of the sub-region. and temperature deviation The graph uses different legends to identify hot spots, cold spots, and normal areas. It visually displays the temperature deviations and types of each sub-region.

[0086] Operation 302: For the sub-region of the type to be adjusted, determine the additional control quantity of each sub-region based on the temperature deviation and partition gain coefficient of each sub-region, and set the additional control quantity of the normal type sub-region to zero.

[0087] Each sub-region is equipped with an independent PI controller within the MCU. For sub-regions determined to be of a type requiring adjustment (i.e., hot or cold areas), the temperature deviation is considered... Calculate additional control values ​​for each partition The calculation formula is as follows:

[0088] in, The partition ratio gain (which can be configured to 1.5 for example). The partition integral gain (which can be configured to 0.1s for example) - ¹), together they constitute the partition gain coefficient; For the first Temperature deviations in individual sub-regions (can be positive or negative); the integral term is accumulated over time to eliminate steady-state deviations.

[0089] For sub-regions determined to be of the normal type, their partition control values ​​are directly set to zero. No further adjustments will be made to it.

[0090] Through the above operations, additional control values ​​are applied only to hot and cold areas where the temperature deviates from the average temperature of the entire field by more than the threshold, while no additional intervention is applied to normal areas, thereby achieving localized differential adjustment while avoiding over-adjustment.

[0091] Operation 303: Calculate the global temperature deviation based on the average temperature of the powder region and the target temperature.

[0092] After completing the continuous temperature field reconstruction, the MCU executes a global temperature control algorithm. This embodiment employs a combination of positional PID control and velocity-based feedforward control.

[0093] Specifically, the MCU first obtains the pre-stored target temperature. The global temperature deviation is then calculated using the following formula:

[0094] in, It can be configured to 170°C, for example.

[0095] Operation 304 determines the global feedback control quantity based on the global temperature deviation and global gain parameters.

[0096] The MCU is equipped with a PID controller, which can use a positional PID discretization algorithm to output a global feedback control quantity. :

[0097] in, The proportional gain (configurable to 3.2) For integral gain (which can be configured as) ), The differential gain (which can be configured as) ), The control period is configurable to 50ms. The global gain parameters consist of proportional gain, integral gain, and derivative gain, which are fine-tuned using the Ziegler-Nichols method based on open-loop step response experiments.

[0098] Operation 305 determines the environmental feedforward compensation amount based on the ambient temperature, reference ambient temperature, and feedforward coefficient.

[0099] The MCU is also equipped with an ambient temperature feedforward controller, which outputs the feedforward compensation amount according to the following formula. To suppress ambient temperature fluctuations in advance:

[0100] in, Forward coefficients (which can be configured as) (Identification offline through environmental disturbance experiments) Reference ambient temperature (can be configured to 25℃). The ambient temperature.

[0101] Operation 306: Determine the total global control quantity based on the global feedback control quantity and the environmental feedforward compensation quantity.

[0102] The global feedback control quantity is expressed by the following formula. and environmental feedforward compensation By summing the results, we obtain the total global control quantity:

[0103] This application embodiment also limits the global total control quantity: if ,but ;like ,but At the same time, to suppress integral saturation, when Reaching the limit and with When the signs are the same, stop accumulating the integral terms.

[0104] Operation 307: Based on the global total control quantity and the additional control quantity of each zone, construct the temperature adjustment command for each sub-zone. The temperature adjustment command carries the global total control quantity and the additional control quantity.

[0105] For each sub-region The MCU adds control variables to its corresponding partition. (The sub-region of the type to be adjusted is calculated through operation 302; the normal type sub-region is zero) and the global total control value. These elements, when combined, form the final temperature regulation command for this sub-region. This temperature regulation command contains two core pieces of information: Global total control quantity This determines the macroscopic heating or cooling tone of the entire powder region; a positive value indicates that heating is required, and a negative value indicates that cooling is required. Additional control variables for each zone Used to overlay local increases or decreases on this sub-region; a positive value indicates that additional increases are needed, and a negative value indicates that decreases are needed.

[0106] The temperature control command is ultimately sent to the temperature control mechanism, where the zone-independent heaters are controlled according to... The final value is used to execute the heating power output, and the cooling module is based on... (when Cooling is performed at any time, and the conveyor speed control module adjusts accordingly. The powder conveying speed is adjusted by changing the temperature. Through this method, coordinated global and local temperature regulation is achieved.

[0107] In one embodiment of this application, the temperature regulation mechanism regulates the temperature of the corresponding sub-regions through the following operations: in response to the global total control quantity in the temperature regulation command being greater than or equal to zero, it enters the heating mode, uses the global total control quantity as the global heating power reference, and superimposes the partition additional control quantity corresponding to each sub-region to obtain the final heating power of each sub-region, and performs heating on the corresponding sub-region according to the final heating power; in response to the global total control quantity in the temperature regulation command being less than zero, it enters the cooling mode, uses the absolute value of the global total control quantity as the cooling intensity, and performs uniform cooling on all sub-regions.

[0108] When the global total control quantity At this time, the temperature regulation mechanism enters the heating mode. At this point, the global total control quantity... As a global heating power benchmark, the corresponding zone-specific additional control quantities of each sub-region are superimposed. The final heating power of each sub-region is obtained. The zone-independent heaters perform heating actions on the corresponding sub-zones based on the final heating power, while the cooling modules are turned off.

[0109] When the global total control quantity At this time, the temperature regulation mechanism enters cooling mode. At this point, the absolute value of the global total control variable is used. As a cooling intensity, uniform cooling is performed on all sub-areas through cooling modules (such as air cooling or water cooling), while all zone-specific independently controlled heaters are turned off.

[0110] In this way, the temperature regulation mechanism automatically switches between heating and cooling modes based on the positive or negative value of the overall control quantity. In the heating mode, it uses the additional control quantity of the zone to achieve local differential power correction, thereby taking into account both overall temperature regulation and local uniformity control.

[0111] To further illustrate the technical solution of this application, a specific application example is provided below.

[0112] In this specific application example, the temperature control system and method of this application are applied to the temperature uniformity control of a selective laser sintering (SLS) powder bed.

[0113] 1. Equipment parameters The powder area (i.e., the powder bed area of ​​the printing equipment) is 280mm×280mm, the powder material is PA12 nylon powder, the target temperature is 170℃, and the allowable fluctuation range is ±2℃.

[0114] 2. System Configuration The flexible high-temperature resistant insulating support layer is made of mica fiberglass composite film, 1mm thick, with a temperature resistance of 500℃, and is attached to the bottom surface of the powder bed (the surface of the hot plate).

[0115] The irregular distributed thermocouple array consists of 16 K-type micro-armored thermocouples (0.5mm wire diameter), arranged according to Poisson disk sampling (e.g., Figure 2 As shown in the figure, the coordinates of each measuring point are pre-calculated and stored in the MCU.

[0116] Each thermocouple measuring end is fitted with a 316L stainless steel thin-walled protective cover, which is 0.2mm thick, 6mm in diameter, and 3mm high. The top of the cover is tightly attached to the thermocouple end face with thermally conductive silicone.

[0117] Each channel of the signal conditioning unit uses a dedicated cold-junction compensation amplifier with a magnification factor of 100 times and an output voltage of 0~5V corresponding to a temperature of 0~500℃.

[0118] The main control unit adopts a combination architecture of MCU and FPGA.

[0119] An ambient temperature sensor with an accuracy of ±0.5℃ should be installed on the side of the powder bed, 50mm away from the powder bed.

[0120] The temperature control mechanism includes infrared radiation lamps with independent zone control, dividing the 280mm×280mm powder bed into 16 independent heating zones of 4×4, with each heating zone corresponding to a sub-area; in addition, it is equipped with a speed-regulating air-cooled fan (corresponding to the cooling module) and a speed-regulating powder spreading roller motor.

[0121] In this specific application example, the temperature control system executes a complete temperature control process every 50ms, with the following specific steps: Data acquisition: The FPGA synchronously samples the voltage signals of 16 thermocouples and the ambient temperature, and performs moving average filtering.

[0122] Temperature field reconstruction: The MCU uses a pre-stored weight matrix W to quickly reconstruct the continuous temperature field of the powder region through radial basis functions (RBF).

[0123] Zoned calculation: Calculate the average temperature of each sub-region based on the continuous temperature field. and the average temperature of the entire venue By comparison, hot and cold regions are identified, and the temperature deviation of each sub-region is calculated. .

[0124] Global control: Calculate global temperature deviation The PID and ambient temperature feedforward algorithm is executed to obtain the global total control quantity. .

[0125] Zone control: The PI controller of each sub-zone is based on... Calculate additional control values ​​for each partition ,Will With global total control quantity By overlaying the data, the final control commands for each sub-region are obtained. .

[0126] Execution output: 16 partition control commands The outputs are sent to the corresponding infrared radiation lamps respectively; and the judgment is made simultaneously. Positive and negative: If Turn off the variable speed air-cooling fan; if Then Turn on the variable-speed air-cooling fan to control the cooling intensity, and turn off the infrared radiation lamps.

[0127] In a specific application example of this application, to verify the effectiveness of this application, a consistency evaluation index was also designed, including the maximum temperature difference. and temperature standard deviation Furthermore, verification has shown that, in this specific application example, under ambient temperature fluctuations of ±5℃, the actual measured steady-state temperature fluctuation range of the powder surface can be controlled between 168.2℃ and 171.5℃ (the maximum measured temperature difference). ), standard deviation of temperature throughout the venue All of these results are better than the design specifications, demonstrating the effectiveness of this application in maintaining the uniformity and stability of powder surface temperature.

[0128] Therefore, this specific application example of the present application can achieve the following technical effects: Flexible bonding: The flexible high-temperature resistant insulating support layer can be bonded to powder bearing surfaces of different shapes, such as curved surfaces and inner walls of pipes, adapting to complex industrial sites.

[0129] Pollution-free: The support layer does not contain PTFE material and has no high-temperature volatiles, making it suitable for scenarios with high cleanliness requirements, such as food, medicine, and high-purity powder.

[0130] Wear-resistant: The metal protective cover isolates the powder from direct contact with the thermocouple, significantly extending the service life of the thermocouple in abrasive powder environments.

[0131] Irregular grid: Irregular distributed thermocouple arrays avoid temperature field spectral aliasing errors caused by regular sampling, thus improving the accuracy of temperature field reconstruction.

[0132] Temperature control performance: steady-state temperature error does not exceed ±2℃, and the response time from the occurrence of temperature deviation to the action of the actuator does not exceed 5 seconds.

[0133] High real-time performance: The single reconstruction time of radial basis function (RBF) interpolation does not exceed 5 milliseconds, and the control cycle can reach 10 to 20 Hz, meeting the requirements of high-speed real-time control.

[0134] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this application can be achieved, and this is not limited herein.

[0135] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0136] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A temperature regulation method, characterized in that, The method includes: The temperature of multiple discrete measurement points within the powder region corresponding to the powder bearing surface of the printing device and the ambient temperature of the powder region are obtained. Based on the temperature of the multiple discrete measurement points, a continuous temperature field is constructed for the powder region. The continuous temperature field includes the temperature of multiple regional points, and the number of regional points is greater than the number of measurement points. The continuous temperature field is divided into multiple sub-regions, and the temperature deviation of each sub-region and the average temperature of the powder region are calculated based on the temperature of each region point within each sub-region. Based on the temperature deviation of each sub-region, the average temperature of the powder region, and the ambient temperature, a temperature adjustment command for each sub-region is determined, and the temperature adjustment command for each sub-region is sent to the temperature adjustment mechanism. The temperature adjustment command is used to control the temperature adjustment mechanism to adjust the temperature of the corresponding sub-region.

2. The method according to claim 1, characterized in that, The acquisition of the temperature of multiple discrete measurement points within the powder region corresponding to the powder bearing surface of the printing device includes: Acquire the voltage data measured by each thermocouple located at each discrete measurement point; Based on the voltage data measured by each thermocouple and the preset voltage-temperature mapping relationship, the measurement point temperature of each discrete measurement point is determined.

3. The method according to claim 2, characterized in that, The acquisition of voltage data measured by each thermocouple arranged at each discrete measurement point includes: Obtain the original voltage signals output by each thermocouple at each discrete measurement point; The original voltage signals output by each thermocouple are amplified, cold junction compensated, and second-order low-pass filtered to obtain the voltage data measured by each thermocouple.

4. The method according to claim 1, characterized in that, The step of constructing a continuous temperature field for the powder region based on the measured temperatures of the multiple discrete measurement points includes: Obtain the weight matrix of the powder region, the weight matrix including the weight coefficient of each region point in the powder region relative to each discrete measurement point; The measurement point temperature of each discrete measurement point is calculated by matrix operation based on the weight matrix to obtain the regional point temperature of each region, thus forming a continuous temperature field covering the powder region.

5. The method according to claim 4, characterized in that, The weight matrix is ​​obtained through the following operation: The powder region is discretized into multiple region points; Based on the location data of each regional point and each discrete measurement point, calculate the relative position of each regional point with respect to each discrete measurement point, as well as the relative position between each discrete measurement point; Construct a coefficient matrix based on the radial basis functions and the relative positions of each discrete measurement point; Based on the radial basis function and the relative positions of each region point with respect to each discrete measurement point, determine the position influence vector of each region point; Based on the position influence vector of each region point and the coefficient matrix, the weight coefficient of each region point relative to each discrete measurement point is determined, and the weight coefficients of each discrete measurement point are concatenated to form the weight matrix.

6. The method according to claim 1, characterized in that, The step of dividing the continuous temperature field into multiple sub-regions and calculating the temperature deviation of each sub-region and the average temperature of the powder region based on the temperature of each point within each sub-region includes: The continuous temperature field is divided into multiple non-overlapping sub-regions according to a preset division rule; Calculate the overall average temperature of all regional points to obtain the average temperature of the powder region; Calculate the average temperature of all points within each sub-region to obtain the average temperature of each sub-region; The temperature deviation of each sub-region is determined based on the average temperature of each sub-region and the average temperature of the powder region.

7. The method according to claim 1, characterized in that, The step of determining the temperature adjustment command for each sub-region based on the temperature deviation of each sub-region, the average temperature of the powder region, and the ambient temperature includes: Based on the temperature deviation of each sub-region and the preset deviation threshold, multiple sub-regions are divided into types to be adjusted and normal types. For the sub-region of the type to be adjusted, the additional control quantity of each sub-region is determined according to the temperature deviation and partition gain coefficient of each sub-region, and the additional control quantity of the partition of the normal type sub-region is set to zero. Calculate the global temperature deviation based on the average temperature of the powder region and the target temperature; Based on the global temperature deviation and global gain parameters, determine the global feedback control quantity; The environmental feedforward compensation amount is determined based on the ambient temperature, the reference ambient temperature, and the feedforward coefficient. The total global control quantity is determined based on the global feedback control quantity and the environmental feedforward compensation quantity. Based on the global total control quantity and the zone additional control quantity, a temperature adjustment command for each sub-region is constructed, and the temperature adjustment command carries the global total control quantity and the zone additional control quantity.

8. The method according to claim 7, characterized in that, The temperature regulation mechanism regulates the temperature of the corresponding sub-regions through the following operations: In response to the global total control quantity being greater than or equal to zero in the temperature adjustment command, the heating mode is entered. The global total control quantity is used as the global heating power reference, and the additional control quantity of each sub-region is superimposed to obtain the final heating power of each sub-region. Heating is performed on the corresponding sub-region according to the final heating power. In response to the global total control quantity in the temperature adjustment command being less than zero, the system enters cooling mode and uses the absolute value of the global total control quantity as the cooling intensity to perform uniform cooling on all sub-regions.

9. A temperature control system, characterized in that, The system includes: A flexible, high-temperature resistant insulating support layer is attached to the powder-bearing surface of the printing equipment; An ambient temperature sensor is arranged on the side of the powder bearing surface without contacting the powder, and is connected to the main control unit to collect the ambient temperature of the powder area corresponding to the powder bearing surface. An irregularly distributed thermocouple array, mounted on the flexible high-temperature resistant insulating support layer and connected to the main control unit, includes multiple thermocouples. Each thermocouple's measuring end is fitted with a metal protective cover, which is in direct contact with the powder, so that the thermocouples indirectly measure the voltage signal of discrete measuring points at corresponding locations through the metal protective cover, allowing the main control unit to obtain the temperature of each discrete measuring point based on the voltage signal. A signal conditioning unit is connected between the irregular distributed thermocouple array and the main control unit. It is used to amplify the voltage signal, compensate for the cold junction, and perform second-order low-pass filtering to obtain the voltage data at the discrete measurement points corresponding to each thermocouple. The main control unit is connected to the irregular distributed thermocouple array, the ambient temperature sensor and the temperature regulation mechanism respectively, and is used to execute the temperature regulation method as described in any one of claims 1-8; A temperature regulation mechanism, connected to the main control unit, is used to regulate the temperature of each sub-region according to temperature regulation commands.

10. A printing device, characterized in that, Includes the temperature control system as described in claim 9.

Images